package org.example.threadpool;

import org.apache.dubbo.common.URL;
import org.apache.dubbo.common.threadpool.support.fixed.FixedThreadPool;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.util.Map;
import java.util.concurrent.*;

/**
 * @author xw
 */
public class WatchingThreadPool extends FixedThreadPool implements Runnable {
    private static final Logger log = LoggerFactory.getLogger(WatchingThreadPool.class);
    //定义线程池使用的阈值
    private static final double ALARM_PERCENT = 0.90;
    private final Map<URL, ThreadPoolExecutor> THREAD_POOLS = new ConcurrentHashMap<>();

    /**
     * 通过父类型创建线程池
     */
    public WatchingThreadPool(){
        //每个三秒钟打印线程使用情况
        Executors.newSingleThreadScheduledExecutor()
                .scheduleWithFixedDelay(this, 1, 3, TimeUnit.SECONDS);

    }

    @Override
    public Executor getExecutor(URL url) {
        final Executor executor = super.getExecutor(url);
        if (executor instanceof ThreadPoolExecutor){
            THREAD_POOLS.put(url, (ThreadPoolExecutor) executor);
        }
        return executor;
    }

    @Override
    public void run() {
        //遍历线程池
        for (Map.Entry<URL, ThreadPoolExecutor> entry: THREAD_POOLS.entrySet()){
            final URL url = entry.getKey();
            final ThreadPoolExecutor executor = entry.getValue();
            //计算相关指标
            final int activeCount = executor.getActiveCount();
            final int corePoolSize = executor.getCorePoolSize();
            double usedPercent = (double) activeCount / corePoolSize;
            log.info("线程池执行状态： {}/{} = {}%", activeCount, corePoolSize, usedPercent*100);
            if (usedPercent > ALARM_PERCENT){
                log.error("超出警戒线！ host： {}, 当前使用率是： {}, URL: {}", url.getIp(), usedPercent, url);
            }
        }
    }
}
